1. Technical Field
The present invention relates to a package-on-package (POP) package and a fabricating method thereof, and more particularly, to a POP package which is prevented from being short-circuited even when an underlying semiconductor package is thick and which can sufficiently withstand deformation caused by post-fabrication warpage, and a fabricating method thereof.
2. Description of the Related Art
In recent years, as electronic products have been incorporating greater functionality, a number of devices need to be integrated in one substrate, which makes it difficult to achieve the desired compactness of the products. Accordingly, researchers are currently seeking a technique of integrating a number of devices in a limited space.
Mounting several chips in one semiconductor package is well known. Furthermore, a package-on-package (POP) package is well known in which a package is formed on another package.
A conventional POP package will be described with reference to FIG. 15.
A first semiconductor package 10 includes a first substrate 11 with a semiconductor chip (not shown) mounted thereon, a mold 14 for holding the semiconductor chip, and external contact electrodes 12 and solder balls 13 for connection to an external board.
A second semiconductor package 20 includes a second substrate 21 and a semiconductor chip (not shown) mounted thereon, a mold 24 for holding the semiconductor chip, and external contact electrodes 22 and solder balls 23 for connection to the underlying first semiconductor package 10.
The second semiconductor package 20 is stacked on the first semiconductor package 10 and connected thereto through the solder balls 23.
In the case where the first semiconductor package 10 is a multi-chip package (MCP) in which several semiconductor chips are stacked, in accordance with a recent trend, the mold 14 is thick and thus the solder balls connecting the first semiconductor package 10 to the second semiconductor package 20 should be large. Recently, as electronic products get more compact, packages get smaller, making it difficult to secure a sufficient interval between the solder balls. In other words, as the solder balls become larger to accommodate the height of the mold in the lower package, it is difficult to achieve sufficient spacing between the solder balls to prevent shorts between them.
As a result, there is a problem in that the solder balls are short-circuited, as shown in FIG. 16B. That is, the solder balls are desired to be evenly arranged as shown in FIG. 16A, but instead, they are lumped and short-circuited as shown in FIG. 16B.
In addition, a connection between stacked packages using solder balls causes the following problems: A fabricated POP package may be bent due to, for example, hardening or heating as time lapses and, in this case, a difference in warpage between the stacked semiconductor packages may cause disconnection between the packages, as shown in FIGS. 17A and 17B.
Accordingly, there is a need for a method for connection in a POP package which is capable of preventing short-circuits due to compactness of products and allowing a semiconductor package to sufficiently withstand deformation caused by post-fabrication warpage.